In air storage gas turbines, the air inlet casing is generally located above the turbine and underneath the upright combustion chamber. It is therefore necessary to provide a straightener with a relatively small opening ratio in order to ensure that an even flow is provided to the combustion chamber. These straighteners however, cause pressure losses. In addition, part of the main air must be supplied to the intermediate space in order to cool the hot gas casing. This known construction leads, furthermore, to long supply lines between the inlet casing and shut-off devices because the latter are normally supported on the foundations of the turbine installations. The result is a relatively large storage volume in the main air region. This large volume can adversely affect the rapid shut-down behaviour of the installation and lead to a large overspeed when the load is shed.